A conventional electrical box is used to mount and house an electrical device (e.g., an outlet receptacle or switch) and its electrical connections. Depending on the application, electrical boxes are called "outlet boxes" or "switch boxes," among other names.
Typically, each electrical box has a rigid housing with two, spaced-apart holes for receiving fastening screws for securing, e.g., the receptacle, to the housing. A cover plate typically fits over the housing, and has openings for providing access to the receptacle. The electrical box is typically installed within a building wall with only the cover, and, thus, the front of the receptacle being accessible. For use out-of-doors, the electrical box is usually adapted with an appropriate rubber gasket between the box and cover, so as to be weatherproof.
In many applications, particularly where electrical devices are being added or additional wiring connections are being made, an electrical box may not have sufficient interior space for the electrical device and the electrical connections. For these purposes, a box extender is used. A box extender effectively supplements the interior space of the electrical box, thereby providing a "larger" effective housing for accommodating the electrical device and/or the additional wiring.
During assembly, an electrician attaches the box extender to the electrical box, typically using screws that extend through a first set of holes provided by the extender, and threadedly engage the fastening holes in the box that are normally used for mounting an electrical device to the box. The electrician also fastens the electrical device to the extender, typically using screws that extend through receptacle holes and threadedly engage a second set of holes provided by the extender for that purpose.
Accordingly, the second set of holes in the extender must be in alignment with, and situated immediately over, the first set of holes in order to be able to effect assembly as just described. As a result, the portion of the extender in which the second set of holes is provided can obstruct access, e.g., by a screw driver, to the first set of holes. Consequently, it can be difficult, under field conditions, to insert and turn the screws used to attach the extender to the box.
This problem has been recognized heretofore, and various solutions proposed. For instance, a known, commercially available arrangement uses specially-adapted fastening screws to attach the electrical device to the extender, and the same fastening screws to attach the extender to the electrical box. The screws have "stepped" shafts, each with a threaded, large-diameter, upper portion and a threaded, small-diameter, lower portion. The electrician can mount the electrical device to the box extender using the upper portions of the screw shafts to engage large-diameter tapped holes in the extender, and can mount the box extender to the electrical box using the lower portions of the shafts to engage the standard holes in the electrical box.
A practical drawback with that approach stems from its dependence on the specially-adapted fastening screws. If those screws are lost or misplaced, which can happen all too readily during field assembly, the box extender can not be installed until replacement screws are supplied. Unfortunately, replacement screws of that type may not be readily available.
Another, very different approach is disclosed in U.S. Pat. No. 3,418,420. The extender of that patent has movable "gates" containing the extender's fastening holes for mounting the receptacle. The movable gates are attached to the extender's housing for pivotal movement. The gates are formed as short, thin-walled, "U"-shaped members. During installation, an electrician can swing the movable gates out of the way to an "open" position for access to the extender's conventionally-located, first set of holes for mounting the extender to the box. Then, the electrician can swing the mounting gates to a "closed" position at which the receptacle can be mounted to the box extender.
In the closed position, narrow portions of the extender's housing are received within central channels of the "U"-shaped movable gates. According to that patent, this arrangement assures that the movable gates are mechanically supported adequately to carry the weight of the receptacle, and to withstand the rigors associated with the assembly and installation process.
While the box extender of that patent is generally suited to its intended purposes, the configuration of the movable gates taught in that patent makes the manufacture of the disclosed extender expensive. Moreover, the movable gates of that patent are short in length, extending only a short distance across the front of the extender's housing and, thus, when open, provide significantly limited access to the box-mounting, first set of holes.
It would be desirable to provide an improved version of that extender, which is of a simpler design that can be manufactured economically, while maintaining or improving the functionality of that patent's movable gates.